It's 100% necessary to cut weight. The "eat until you're full" method is complete bullshit.
Totally. I always end up gaining the weight back when “just winging it”. Especially necessary if you’re training hard and trying to put on muscle, which I think is the other really effective way to reduce belly fat. But typically you have to cut the lion’s share of excess weight first, hard to do both at the same time. I also found that overeating even in a single weekend meal (half a pizza, beers and some dessert, for example) really set me back.